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  <title>Document</title>
  <!-- 写出⼀个1到10 的数组，少写⼀个数字，利⽤函数将少写的数字找出来。 -->
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  <script>
    function info(){
      let arr = [1,2,3,4,5,6,7,8,10];
      let res = 0;
      let num = 55;
      for(let i = 0; i < arr.length; i++){
        res += arr[i]
      }
      return num - res
    }
    console.log(info());
    

  </script>
</body>
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